Typical end closures for beer and beverage containers have an opening panel and an attached leverage tab for pushing the opening panel into the container to open the end. The container is typically a drawn and ironed metal can, usually constructed from a thin plate of aluminum or steel. End closures for such containers are also typically constructed from a cutedge of thin plate of aluminum, formed into a blank end, and manufactured into a finished end by a process often referred to as end conversion. These ends are formed in the process of first forming a cutedge of thin metal, forming a blank end from the cutedge, and converting the blank into an end closure which may be seamed onto a container.
These types of container ends have been used for many years, with almost all such ends in use today being the “ecology” or “stay-on-tab” (“SOT”) ends in which the tab remains attached to the end after a tear panel, including large-opening ends (“LOE”), is opened. The tear panel being a portion of the can end defined by a score length. The tear panel may be opened, that is the score may be severed, and the tear panel displaced at an angular orientation relative to the remaining portion of the can end. The tear panel remains hingeably connected to the remaining portion of the can end by a hinge segment, leaving an opening through which the user draws the contents of the container. In an LOE, the opening is at least 0.5 square inches in area.
Opening of the tear panel is operated by the tab which is attached to the can end by a rivet. The tab is attached to the can end such that a nose of the tab extends over a proximal portion of the tear panel. A lift end of the tab is located opposite the tab nose and provides access for a user to lift the lift end, such as with the user's finger, to force the nose against the proximal portion of the tear panel.
When the tab nose is forced against the tear panel, the score initially ruptures at a vent region of the score. This initial rupture of the score is primarily caused by the lifting force on the tab resulting in lifting of a central region of the can end, immediately adjacent the rivet. As the tab is lifted further, the score rupture propagates along the length of the score, eventually stopping at the hinge segment.
One problem associated with the SOT and LOE ends is rotation of the tab on the rivet in a clockwise or counterclockwise direction prior to opening. When the tab rotates on the rivet, the probability of an opening failure increases. An opening failure is defiled as an instance when the can end is opened in a manner other than that described above, or when the container cannot be opened using the SOT (i.e., some force must be supplied by an instrument other than the SOT).
One method aimed at eliminating tab rotation includes placing an “up” dimple on the can end near the rivet area. The up dimple is aligned with, and fits within, a small hole on the tab. The up dimple is created by tooling that strikes the product or beverage side of the can end. One drawback of this proposed solution is that the tooling that creates the up dimple damages a film that coats the product side of the can end, and such damage might allow direct contact between the metal of the can end and the contents of the container.
As is explained in greater detail below, the present invention reduces or eliminates these problems.